Energy Efficiency Measure No. EMS 001

REPLACE EXISTING MOTOR WITH A HIGH EFFICIENCY ONE
ENERGY SAVING AREA:                  electric motors

COMPONENT CATEGORY:                Efficiency Improvement

ACTION TYPE(S):                       Replace   /  Install

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TECHNICAL DESCRIPTION COST INFORMATION EVALUTATION & DECISIONAL PROCEDURES COMMERCIAL INFORMATION

TECHNICAL DESCRIPTION

DESCRIPTION of the Measure (Suggested Action): Replace the old (non-High Efficiency Motor) motor with a high efficiency one, when the load factor is sufficiently high to ensure a cost-effective replacement. 

TYPICAL APPLICATIONS: The replacement of a standard motor with a HE motor is recommended in all situations where the motor is running for a large numbers of hours per year (e.g. 2000-3000 h/a)

CAUTIONS SUMMARY and CONSIDERATIONS:  The Motors have lower slip, thus run faster and this can reduce or eliminate savings. A carefull speed vs. efficiecy pays off. Moreover, HEM tend to have higher inrush currents; especially where the motor size is increased, they may require upgrades to the electrical distribution system to reliably start the motor without tripping overload devices.

PROBLEMS due to LACK of THIS ECO (Background):  High electrical energy use due to none HEM standard

SIDE BENEFITS: The HE motor not only saves energy because has lower losses, but also, due to its lower opearting temperature, has a longer lifetime with respect to a standard motor. Moreover, HEMs operate with reduced noise and improved power factor. This latter benefit, although depending very much upon the electrical tariff and the amount of PF correction equipment, can result in important financial savings.

DISADVANTAGES: none known

COST INFORMATION

IMPLEMENTATION COST: is limited to the extra-cost of new High Efficincy Motor. Sometimes adaptation costs must be foreseen if the size of new motor is different.

COST EFFECTIVENESS: depends on the price premium, the efficiency of the old motor and the operating hours of the motor. Usually payback time can be about 5 years.

O & M REQUIREMENTS AND RELATED COST VARIATION: No change

REMARKS on COST FACTORS. PRICE PREMIUM of High Eff. Motors is about 20-25% with respect to STANDARD MOTORS of large rated power. Small HEM’s are now supplied at no cost premium. However, small cost due to smaller footprint of motor and modifications maybe required to fixing.

DECISIONAL & EVALUATION PROCEDURE

IMPLEMENTATION STRATEGY: REPLACE IMMEDIATELY, WHEN THE OLD MOTORS BREAKDOWNS OR WHEN THE REPLACEMENT IS COST-EFFECTIVE.

IMPLIED ECOS: In case of variable load, the new motor must be selected together with an improved control system.

GENERAL COMMENTS and RECOMMENDATIONS
BASELINE TECHNOLOGY to be upgraded:   Electric Motors with Low -Normal efficiency (Efficiency Class 3)
ENERGY SAVING POTENTIAL: 1-9% (average 3%) FOR APPLICABLE MOTORS

AUDIT & IMPLEMENTATION DECISION PROCEDURE: By knowing the operating hours/a and the cost of electricity and the cost of power supply, it is possible to determine the overalll yearly money savings per annum. This figure must be used together with the net Investment cost (Net Investment = TC-hem - Cold + RVold) to determine the cost-effectiveness indicator (e.g. payback time, IRR, CSE or other).   Total Cost of a HEM (TC-hem) is given by the purchase cost of the HEM + Installation cost - Eventual Rebates/Incentives. Cold is the cost of the existing motor as a new, and RVold is the residual value of existing motor.

             If the payback time is within the limits set by the company, then implement this ECO.

ENERGY SAVING EVALUATION PROCEDURE: Having selected motor that is are running at high load and running hours(Check first the motor operating hours), identify the energy used by simply noting the power consumed from the motor rating plate (spot measurement of motor input power can be measured using a power meter if confirmation of high load is required).

Calculate the demand power savings and the energy saved  with the following formulas:

KWsaved = kWnameplate x LF (100/Eff-std - 100/Eff-he)

KWhsaved = kWsaved x Annual Operating Hours

In order to determine the motor efficiency

Eff-std=Mech. Output/Power input =Motor Load * Nameplate kW/Power input 

measure the

a) the Power draw from the mains (Power consumption of each motor can be monitored with clip-on current transformers to measure individual phase currents. Also apparent power and PF can be measured in the same time):

(3 phase)Pav = Volt avg * Amps avg * (PF/100) *1,732/100

(1 phase)Pav =Volt avg * Amps avg * (PF/100) /1000

b) the running Speed Rspeed to determine the Slip and then the Motor Load

Motor Load = Slip/(RPMsync-RPM FullLoad nameplate)

          

EX-POST ACCEPTANCE & PERFORMANCE COMPLIANCE CHECK PROCEDURE: Check the efficiency of the new HEM and compare it with predicted efficiency figure. Make sure that predicted savings are obtained.

USER INFORMATION and COMMERCIAL ISSUES

ECO ENVIRONMENTAL IMPACT & CONSTRAINTS: The implications of scrapping motors rather than repair can be justified as a result of the CO2 savings from more efficient units
USER'S/CLIENT's ACCEPTANCE:
PURCHASE AND O&M PROBLEMS:  Easily available, with no problems
PRACTICAL IMPLEMENTATION PROBLEMS: May need to modify fixing arrangements to suit HEM - need to consider if change in slip problematic to process. By making sure the motor is the right size and type for the application and by assisting the installer with proper accessories (belt sheaves, transition bases, etc.) the retrofit process is greatly facilitated.
EASE OF USE: No problems at all
OTHER NON-TECHNICAL BARRIERS:
COMMERCIAL INFO. ON MANUFACTURERS:
REFERENCES, LITERATURE & LINKS : Good Practice Case Study n. 162 – EEO

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